The interesting thing about CouchDB is that it's actually more like an HTTP storage and query API/protocol than a particular database implementation.

As you've noted, there's lots of implementations and variants, platform targets and hosted services. What ties them all together is that you can point your CouchDB client library (or curl! :-P) at any of them, and be off and running.

While having a tip of the spear with a consistent message, canonical implementation and download, etc. is one approach (and I could certainly live with better messaging from certain places!), I think people are convinced enough by the merits of the CouchDB model to effectively route around the lack of that and some have produced fantastic (compatible / interoperable) alternatives.

(FWIW, I've been using CouchDB for a long time with a lot of apps and instances, but have been able to use all of them with Cloudant instead.)

Insofar as MongoDB's fate is tied to 10gen's, the distributed nature of the CouchDB ecosystem is actually working out quite well AFAICT.